Back support chair



FIG. 1 is a perspective view of a back support chair taken from above and from the left side showing my new design, the chair base and chair controls being shown in chain-dotted lines not being part of the design;

FIG. 2 is a right side elevational view thereof, the left side being a mirror image;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a plan view thereof; and,

FIG. 5 is a rear elevational view thereof. 

The ornamental design for a back support chair, as shown and described. 